Bosch Dishwasher Flow Switch or Control Panel

We are experiencing the same problem that others report related to long cycle times and starting on 2H requiring a reset at some point and then the timer drops to 90 min or less and then the cycle finishes fine. I ran the diagnostic and the indicator reads 0 and the test runs and runs. This is described as a flow switch failure. Should I first replace the flow switch ($15) and see if that solves the problem or start with the control panel (repair/replace) which seems to be the most common solution . How hard is it to find the flow switch and where is it located?